1. Field Of Invention
The present invention relates generally to a sonication method of encapsulating a hyperbaric gas for use in treating atherosclosis, infections and neoplasms, and for providing systemic oxygenation of tissues.
2. Related Art Statement
Most living organisms require oxygen to maintain homeostasis and viability. Tissues in man and other mammals are oxygenated by virtue of the dissolution and binding of oxygen in blood within capillaries of the lung after diffusion of oxygen across thin alveolar membranes of the lung. The quantity of oxygen bound to hemoglobin and, to a lesser extent, dissolved within serum is usually adequate to maintain an optimal level of oxygenation of all tissues by diffusion of oxygen from blood capillaries to tissue. Although the rate of diffusion of oxygen through soft tissues is actually quite slow, the intercapillary distance is usually small, so that only very short diffusional distances are required, For some tissues, however, the diffusional distances for oxygen are large, and local tissue hypoxia results. The lack of an optimal supply of oxygen interferes with local tissue homeostasis, and pathologic tissue growth is initiated and/or promoted.
Efforts have been made to improve blood oxygenation by inspiration of oxygen at higher than normal oxygen concentration in air. These efforts have not been satisfactory factory because: 1) prolonged inspiration of oxygen at a high partial pressure produces lung toxicity, and 2) blood is nearly saturated with oxygen during ordinary air breathing--accordingly, an increase in the inspired oxygen concentration above that in air does little to increase the content of oxygen within blood.
One approach to problems of improving blood oxygenation would be to encapsulate oxygen under pressure in a manner which allows parenteral injection of oxygen. Gas-containing capsules have been prepared from a variety of substances, including glass. Methods to make such glass particles are known. By way of example, one method is disclosed in U.S. Pat. No. 3,972,721 to Hammel et al, entitled "Thermally Stable and Crush Resistant Microporous Glass Catalyst Supports and Methods of Making", the relevant teachings of which are incorporated herein by reference. The technology presently exists for the manufacture of hollow glass microballoons as small as two microns. For example, FTF-15 glass microballoons can be purchased from Emerson and Cumming of W.R. Grace, Inc. Thus, it is feasible to make hyperbaric gas-filled glass microballoons sufficiently small to pass through all capillaries of the body (approximately 5 microns in diameter) without entrapment following intravenous injection of a suspension of the glass shells. However, only low molecular weight gases such as helium can permeate the glass shells during heating of the latter under hyperbaric gas conditions, so that the gas will be trapped within the microballoons upon subsequent cooling of the glass. Since the permeability of higher molecular weight gases through glass even at elevated temperatures is quite low, a sufficient quantity of oxygen cannot be entrapped.
One method for forming fine glass foam is disclosed in U.S. Pat. No. 4,332,907 to Vieli entitled "Granulated Foamed Glass and Process for the Production Thereof", filed Oct. 4, 1979, the relevant teachings of which are incorporated herein by reference. Another method is disclosed in U.S. Pat. No. 3,963,503, entitled "Method of Making Glass Products, Novel Glass Mix and Novel Glass Product", the relevant teachings of which are also incorporated herein by reference. U.S. Pat. No. 4,347,326 to Iwami et al entitled "Foamable Glass Composition and Glass Foam", filed Aug. 31, 1982, the relevant disclosure of which is also incorporated herein by reference, also teaches a method for making a glass foam. See also, U.S. Pat. No. 4,332,908 to Vieli filed Nov. 27, 1979 entitled "Foamed Granular Glass", and U.S. Pat. No. 4,104,074 entitled "Pulverulent Borosilicate Composition and a Method of Making a Cellular Borosilicate Body Therefrom", the relevant teachings of which patents are also incorporated herein by reference.
However, none of those methods are capable of viably producing sufficiently small microbubbles to permit injection, containing gases at sufficiently high pressures which are critical to the process disclosed below.
Accordingly, it is an object of the present invention to provide a method for encapsulating hyperbaric oxygen in order to treat diseases associated with hypoxia of tissues.
It is also an object of the present invention to provide products made by the disclosed process.